The research is designed to elucidate the manner in which the decision to move the eyes is translated into the pattern of excitatory and inhibitory neural impulses channeled to the muscle fibers of the twelve extraocular muscles in the primate. Some of the experiments are carried out on monkeys. Visual and vestibular stimulation is given to alert monkeys and the relationship between responses to different stimulus parameters is used to characterized the relationship between neural pathways. Specific ablations in these pathways permit identification of the role of certain sturctures (e.g. flocculus and other parts of the cerebellum) in eye movement control. Such experiments, and the knowledge obtained from post-mortem histology, will enable the tracing of the supranuclear pathways which are utilized by the saccadic, pursuit, vergence and vestibular eye movement systems. Studies on human subjects are designed to delineate the information from retinal image motion that is available to release pursuit eye movements.